Document MSRV 1.31.0

Author: eldruin

.travis.yml

@@ -2,6 +2,7 @@ language: rust
 
 matrix:
   include:
+    # MSRV
     - env: TARGET=x86_64-unknown-linux-gnu
       if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
       rust: 1.31.0

README.md

@@ -4,6 +4,11 @@
 
 This project is developed and maintained by the [Cortex-R team][team].
 
+# Minimum Supported Rust Version (MSRV)
+
+This crate is guaranteed to compile on stable Rust 1.31.0 and up. It *might*
+compile with older versions but that may change in any new patch release.
+
 ## License
 
 Licensed under either of